Clinch fasteners have two primary features related to their retention in the host material, usually metal sheets. They are displacers and undercuts. Installing clinch fasteners into host materials is a process of pressing the fasteners' displacers into the host material. The displaced volume of the host material is then by default pushed into the undercut of the clinch fastener thus retaining it in the sheet. Pressing clinch fasteners into host materials requires different forces during the pressing process due to the geometry of the fasteners' displacers. During the pressing process the force required varies but when seated properly there is an instant and abrupt rise in the force required to continue pressing. If the force is increased beyond the point of proper insertion, over-insertion results and the effect is usually a distortion of the clinch fastener and/or the host material. If the pressing force is insufficient then under-installing is the result and typically the clinch fasteners' retention values are diminished.
Currently, selecting the correct insertion force for a clinch fastener is limited to two options. The first option is selecting a force from a table of forces grouped into categories of fastener size, type, and the type of host material the fastener is to be inserted into. These categories are broad generalizations and only provide an estimated force. This estimated force is considered a baseline to work from and the ideal force is then arrived at by trial and error. The trial and error method consists of pressing to a pre-chosen force and then adjusting that force on subsequent insertions to determine the optimal force. The second method of determining the proper insertion force is to bring the ram into contact with a properly positioned fastener on the host sheet and then incrementally increasing the force until the desired insertion results are achieved. Again, this usually involves a measure of trial and error to achieve desirable results and requires considerable operator skill if it is to be carried out quickly and efficiently. This makes the second method relatively expensive. Regardless of which method is used, the optimal force is then recorded and all subsequent fastener installations in that batch are installed to that force.
There is therefore a need in the art for a reliable system for determining proper insertion force in a fastener press which is accurate and reliable. There is a further need for an accurate and reliable proper-insertion-force determination process which may be carried out in automated fashion so that minimal operator skill is required.